It is known that the steel cord for the reinforcement of rubber products, for example pneumatic tires and conveyor belts, is made by twisting multiple wires together. In the twist process, each wire must be kept at a constant tensile before entering twist machine. In order to maintain the constant tension, most known devices are provided with an electronic detector to measure the tension of wires at a certain point and send the date to a processor and a motor to control the transport speed and the tension. It is not reliable that the electronic control has a time delay that leads to inaccuracy.
Prior art US2008/092510A1 discloses a mechanical tensile control device of a triple twist pay-off system, wherein wire tension is stabilized by the swing of weight block on the pivoted arm. But this device also has some drawbacks. Firstly, each of this tensile control device can only accommodate one wire, and multiple devices are needed according to the number of wires. Secondly, because of the difference on device manufacturing and assembly, the tension setting on devices can be different. Therefore, there is a need to provide a mechanical device which can not only accommodate multiple wires but also balance the tension difference between multiple wires.